import { saveAs } from "file-saver";
import XLSX, { WorkBook, WorkSheet } from "xlsx";

interface ICell {
  v: Date | number | boolean | string;
  t: string;
  z: string;
}

class Workbook implements WorkBook {
  SheetNames: string[] = [];

  Sheets: { [sheet: string]: WorkSheet } = {};
}

const generateArray = (table: HTMLElement) => {
  const out = [];
  const rows = table.querySelectorAll("tr");
  const ranges = [];
  for (let R = 0; R < rows.length; ++R) {
    const outRow = [];
    const row = rows[R];
    const columns = row.querySelectorAll("td");
    for (let C = 0; C < columns.length; ++C) {
      const cell = columns[C];
      const colspanStr = cell.getAttribute("colspan");
      const rowspanStr = cell.getAttribute("rowspan");
      let colspan;
      let rowspan;
      if (colspanStr) {
        colspan = parseInt(colspanStr);
      }
      if (rowspanStr) {
        rowspan = parseInt(rowspanStr);
      }
      const cellValue = cell.innerText;
      // Skip ranges
      ranges.forEach((range) => {
        if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) {
          for (let i = 0; i <= range.e.c - range.s.c; ++i) outRow.push(null);
        }
      });
      // Handle Row Span
      if (rowspan || colspan) {
        rowspan = rowspan || 1;
        colspan = colspan || 1;
        ranges.push({
          s: {
            r: R,
            c: outRow.length,
          },
          e: {
            r: R + rowspan - 1,
            c: outRow.length + colspan - 1,
          },
        });
      }
      // Handle Value
      outRow.push(cellValue !== "" ? cellValue : null);
      // Handle Colspan
      if (colspan) {
        for (let k = 0; k < colspan - 1; ++k) {
          outRow.push(null);
        }
      }
    }
    out.push(outRow);
  }
  return [out, ranges];
};

const datenum = (date: Date) => (+date - +new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);

const sheetFromDataArray = (data: any) => {
  const ws: { [key: string]: any } = {};
  const range = {
    s: {
      c: 10000000,
      r: 10000000,
    },
    e: {
      c: 0,
      r: 0,
    },
  };
  for (let R = 0; R !== data.length; ++R) {
    for (let C = 0; C !== data[R].length; ++C) {
      if (range.s.r > R) range.s.r = R;
      if (range.s.c > C) range.s.c = C;
      if (range.e.r < R) range.e.r = R;
      if (range.e.c < C) range.e.c = C;
      const cell: ICell = {
        v: data[R][C],
        t: "",
        z: "",
      };
      if (cell.v == null) continue;
      const cellRef = XLSX.utils.encode_cell({
        c: C,
        r: R,
      });
      if (typeof cell.v === "number") cell.t = "n";
      else if (typeof cell.v === "boolean") cell.t = "b";
      else if (cell.v instanceof Date) {
        cell.t = "n";
        cell.z = XLSX.SSF.get_table()[14];
        cell.v = datenum(cell.v);
      } else cell.t = "s";
      ws[cellRef] = cell;
    }
  }
  if (range.s.c < 10000000) {
    ws["!ref"] = XLSX.utils.encode_range(range);
  }
  return ws;
};

const s2ab = (s: string) => {
  const buf = new ArrayBuffer(s.length);
  const view = new Uint8Array(buf);
  for (let i = 0; i !== s.length; ++i) {
    view[i] = s.charCodeAt(i) & 0xff;
  }
  return buf;
};

export const exportTable2Excel = (id: string) => {
  const theTable = document.getElementById(id);
  if (theTable) {
    const oo = generateArray(theTable);
    const ranges = oo[1];

    /* original data */
    const data = oo[0];
    const wsName = "SheetJS";

    const wb = new Workbook();
    const ws = sheetFromDataArray(data);

    /* add ranges to worksheet */
    // ws['!cols'] = ['apple', 'banan']
    ws["!merges"] = ranges;

    /* add worksheet to workbook */
    wb.SheetNames.push(wsName);
    wb.Sheets[wsName] = ws;

    const wbout = XLSX.write(wb, {
      bookType: "xlsx",
      bookSST: false,
      type: "binary",
    });

    saveAs(
      new Blob([s2ab(wbout)], {
        type: "application/octet-stream",
      }),
      "test.xlsx",
    );
  }
};

export const exportJson2Excel = (header: string[], data: any, filename = "excel-list", multiHeader: string[][] = [], merges: any[] = [], autoWidth = true, bookType = "xlsx") => {
  data = [...data];
  data.unshift(header);
  for (let i = multiHeader.length - 1; i > -1; i--) {
    data.unshift(multiHeader[i]);
  }

  const wsName = "SheetJS";
  const wb = new Workbook();
  const ws = sheetFromDataArray(data);

  if (merges.length > 0) {
    if (!ws["!merges"]) {
      ws["!merges"] = [];
    }
    merges.forEach((item) => {
      ws["!merges"].push(XLSX.utils.decode_range(item));
    });
  }

  if (autoWidth) {
    // 设置worksheet每列的最大宽度
    const colWidth = data.map((row: any) => row.map((val: any) => {
      // 先判断是否为 null/undefined
      if (val == null) {
        return {
          wch: 10,
        };
        // 再判断是否为中文
      }
      if (val.toString().charCodeAt(0) > 255) {
        return {
          wch: val.toString().length * 2,
        };
      }
      return {
        wch: val.toString().length,
      };
    }));
    // 以第一行为初始值
    const result = colWidth[0];
    for (let i = 1; i < colWidth.length; i++) {
      for (let j = 0; j < colWidth[i].length; j++) {
        if (result[j].wch < colWidth[i][j].wch) {
          result[j].wch = colWidth[i][j].wch;
        }
      }
    }
    ws["!cols"] = result;
  }

  // Add worksheet to workbook
  wb.SheetNames.push(wsName);
  wb.Sheets[wsName] = ws;

  const wbout = XLSX.write(wb, {
    bookType: bookType as any,
    bookSST: false,
    type: "binary",
  });

  saveAs(
    new Blob([s2ab(wbout)], {
      type: "application/octet-stream",
    }),
    `${ filename }.${ bookType }`,
  );
};
